Graphene, a two dimensional monolayer of sp2-hybridized carbon atoms arranged in a honeycomb network, exhibits excellent mechanical, thermal, electrical, and optical properties; large specific surface area; and chemical stability. These superb properties offer graphenes many potential applications ranging from nanoelectronics, composite materials, sensors to electrochemical electrodes in lithium ion batteries, solar cells, or ultracapacitors. Specific electronics applications of graphene include mobile phones, radars, transistors, data storage, touch screens, and wearable electronics.
Although there is an increasing interest in both the theoretical and experimental study of graphene, high quality, low cost, and scalable graphene production is still a major challenge. There are basically four methods of making graphene. The first method is the mechanical exfoliation of graphite, which can produce high quality graphene. However, the yield is low because it is hard to control the layers of graphene in the product. Therefore, this method is only useful for fundamental study. The second is chemically derived graphene colloidal suspensions. This method can produce scalable graphene sheets in solution, but the electrical conductivity is poor since the chemical oxidation and reduction process may lead to structural defects. The third method is organic synthesis. However, graphene produced by total organic synthesis has size limits due to insolubility of macromolecules and side reactions. Lastly, chemical vapor deposition (CVD) is a promising method for growing high quality and large-scale graphene. The existing CVD methods require expensive transition metals such as Co, Ni, Pt, Ir, and Ru as catalyst, hydrocarbon gas as carbon source, and e-beam evaporation process. Some CVD methods also need ultrahigh vacuum conditions and/or specific substrates for graphene growth. High costs hinder the use of the CVD methods for large-scale graphene production and applications.